This invention relates generally to variable sweep wing aircraft, and, more particularly, to the wing pivot assembly for joining the outboard movable wing to the fuselage of the aircraft.
It is well known that present conventional wing designs, which are substantially without sweep, give better take-off climb and low speed performance than swept-back wings, and that a high degree of sweep is desirable in the transonic speed range. The problem therefore, has been to get sweep wing designs safely into the air and up to a speed at which the swept design comes into its own; as well as to land such designs at reasonable touchdown speeds.
The sweep wing design encounters difficulties in stall control and poor maximum lift coefficient during low speed operation; whereas, the essentially straight wing is most efficient under these conditions and encounters extremely serious troubles at sub- and transonic speeds where the sweep wing is at its best. The incorporation of a variable sweep wing so that higher degrees of swept angle could be employed for maximum speed performance, and essentially zero degrees of sweep could be employed during very low speed flight results in greatly improved maneuverability characteristics and permits a large range of maneuvering speeds at high altitudes for substantial maneuvering load factors. Comparative design studies for a given range and performance have shown that a fixed sweep wing airplane would have to be much larger and provided with approximately twice the power necessary in the present variably sweep wing design.
Unfortunately the incorporation of the variable sweep wing design within an aircraft results in large loads being applied to the pivot assembly joining the wing to the fuselage of the aircraft. Such forces which concentrate at the wing pivot, if not adequately compensated for, can result in catastrophic consequences to both the aircraft and/or personnel involved in the use of the aircraft. The utilization, however, or more sturdy and complex wing pivot assemblies have also encountered problems in themselves since the reliability of operation of the variable sweep wing feature of the aircraft is substantially affected by an increase in parts and weight at the pivot point thereof. It is therefore essential in variable sweep wing pivot assembly design to produce not only a pivot assembly which is extremely strudy in construction, but also one which provides reliable variable sweep wing operation without an exorbitant increase in expense over prior assemblies.